1. Field of the Invention
The present invention relates to a method of manufacturing a compressed lump of metal scrap that is capable of compressing various kinds of collected metal scrap into a standardized form so that the metal scrap can be directly charged into a blast furnace.
2. Description of the Related Art
As is generally known, various kinds of metal scrap, including materials dug from various production fields or used molds disposed from various production fields, reinforcing rods obtained from demolished buildings, and metal waste, such as scrapped vehicles, disused gas containers or cans obtained from various consumption fields, are collected, sorted, and melted to manufacture various kinds of steel materials, thereby reducing resources and energy used to manufacture steel materials and eventually protecting environment,
To this end, metal scrap is basically sorted according to kinds of the metal scrap and is compressed into a compressed lump of metal scrap which is formed and standardized so that the compressed lump of metal scrap can be directly charged into a blast furnace of a steel mill, to which the compressed lump of metal scrap is supplied.
Such a compressed lump of metal scrap is generally configured so that the sum of the width, length, and height of the compressed lump of metal scrap is between 600 mm and 2100 mm. Also, metal scrap is compressed so that a compressed lump of metal scrap has the maximum length of less than 800 mm and a density of 0.15 or more.
In a conventional apparatus for manufacturing such a compressed lump of metal scrap, metal scrap, including ferrous metal scrap and nonferrous metal scrap, such as aluminum and copper, collected via various routes is sorted and compressed by a compress apparatus to form a compressed lump of metal scrap in the shape of a hexahedral body having a predetermined standard. A representative example of the apparatus for manufacturing the compressed lump of metal scrap is disclosed in Japanese Utility Model Publication No. S38-11798 entitled “Scrap press apparatus” (hereinafter, referred to as a ‘cited invention’).
The cited invention provides a scrap press apparatus configured to have a structure in which a slide type upper cover 1 is installed above a scrap molding chamber 2 having a press plate 5 and transverse press plates 20 provided at left and right sides thereof, a stationary cover unit 3 is installed above a material molding side of the scrap molding chamber 2, a lower cover 7, which can be freely opened and closed, to discharge a shaped product is installed under the material molding side of the scrap molding chamber 2, a shearing cutter 4 is installed at a contact portion between the stationary cover unit 3 and the slide type cover, and a shearing cutter 4 is installed above the press plate 5.
In the cited invention, metal scrap is charged into the scrap molding chamber 2, the upper cover 1 is closed, and a primary cylinder 14 is driven to advance a piston 13. As a result, the press plate 5 primarily compresses metal scrap in the scrap molding chamber 2 into a form as indicated by a dotted line of FIG. 2. Subsequently, the opposite transverse press plates 20 are advanced to the middle of the scrap molding chamber 2 by pistons 22 of cylinders 21 to secondarily compress the primarily compressed metal scrap. After the metal scrap is secondarily compressed, a lower cover actuating cylinder 8 connected to the lower side of the lower cover 7 is driven to pull the middle of a link 10. As a result, the lower cover 7 is opened to the lower side, and therefore, a compressed lump 23 of metal scrap falls and is carried outside by a conveyor 18.
A required number of compressed lumps of metal scrap of a predetermined standard manufactured according to the cited invention with the above-stated construction are directly charged into a blast furnace to manufacture various kinds of steel products. Consequently, a very efficient operation is possible.
On the other hand, such a compressed lump of metal scrap is obtained by compressing a large amount of metal scrap with high density so that the volume of the compressed lump of metal scrap is small. For this reason, the compressed lump of metal scrap has large thermal capacity, and therefore, it is necessary to heat the compressed lump of metal scrap for a long time using a large amount of energy so as to melt the compressed lump of metal scrap. Consequently, a large amount of energy is consumed in a melting process with the result that costs necessary to manufacture steel products are greatly increased. Also, a discharge amount of carbon is increased since large amount of energy is consumed with the result that environment is polluted.
As a rule, metal scrap must be sorted according to ingredients of the metal scrap so that pure nonferrous metal scrap or pure ferrous metal scrap can be separately compressed to manufacture such a compressed lump of metal scrap. However, some thoughtless processors mix concrete, which is heavy, with metal scrap to manufacture a poor compressed lump of metal scrap. If such a poor compressed lump of metal scrap is charged into a blast furnace, the blast furnace is contaminated by impurities. Enormous expense is needed to remove contaminants from the blast furnace, and, in addition, a production project is frustrated. As a result, steelmakers have difficulty in using a compressed lump of metal scrap.